It is known that heat transfer articles and devices can be used to provide temporary relief from aches, pains, and muscle soreness in limbs. In common use, an article or device is heated in some manner and placed on the skin. An article that relies on an external energy source for heat may for example be heated in a conventional oven or, more typically nowadays, in a microwave oven.
An example of such an article is a bag or envelope containing grains of cereal such as oats, as is well known. A thermally conductive envelope, for example made of cotton, may be filled with oats for heating in a conventional oven or microwave oven. In use, the heat generated in the oats by the energy source is transferred to the user's skin and subcutaneous tissue, for soothing and/or therapeutic relief.
Therapeutic articles which provide a cooling effect are also well known to provide a soothing effect for swelling or pain when applied to the skin. Such an article may be cooled in a freezer and then placed in contact with the skin, absorbing heat from the skin to provide the desired cooling effect. The envelope containing oats as described above is an example of such a therapeutic cooling article. However, using a cotton envelope containing oats as a therapeutic cooling article, often results in a damp sensation when the article is placed against the skin. A therapeutic cooling article may alternatively consist of a gel pack filled with a gel having a high thermal inertia and a low freezing point, and is available in both reusable and one-time use forms. When cooled the gel pack assumes the temperature of the freezer, which can be colder than human skin can comfortably accommodate, and as such a gel pack often must be wrapped in a towel or other fabric to partially insulate the cold of the gel pack from the hand or body in order to prevent discomfort.